As well known, polyesters have been widely used as fibers, resins, films and the like due to excellent performances thereof. Especially, polyester fibers comprising polyethylene terephthalate and having excellent dimensional stability, heat, chemical and light resistances and the like have been utilized in various fields irrespective of clothing and nonclothing uses.
In the situation, attention has recently been paid to polyester fibers based on polytrimethylene terephthalate and a woven or a knitted fabric comprising the polyester fibers so as to exhibit hand and dyeability which are difficult to realize from the conventional polytrimethylene terephthalate [for example, JP-A (hereunder, JP-A means “Japanese Unexamined Patent Publication”) 11-200175]. The polyester fibers based on the polytrimethylene terephthalate, however, have problems that degree of yellowing in light irradiation is greater than that of polyethylene terephthalate and light resistance is inferior to that of the polyethylene terephthalate.
As a method for improving the whiteness of the polytrimethylene terephthalate, the addition of a phosphorus compound during polymerization is proposed in, for example WO99/11709. An improvement in light resistance, however, cannot be expected by the method though the melt stability is improved.
On the other hand, for example, JP-A 3-234812 describes a method for adding a manganese compound, an antimony compound and a germanium compound to polyethylene terephthalate as a method for improving the light resistance of the polyester fibers. The method relates to the inhibition of the strength deterioration of the polyethylene terephthalate fibers and is a technique different from the prevention of yellowing, especially the prevention of yellowing of the polytrimethylene terephthalate fibers.
U.S. Pat. No. 5,872,204 describes the use of a manganese compound as a catalyst usable together with an antimony compound catalyst as a technique for adding a manganese compound to the polytrimethylene terephthalate. However, there is no description of an improvement in light resistance by the method, which has problems that foreign materials are readily produced in spinnerets during fiber formation because the antimony compound is used.